Electromagnetic switching devices



July 28, 1959 A. HUFNAGEL 2,897,317

ELECTROMAGNETIC SWITCHING DEVICES Filed Oct. 29, 1957 3 Sheets-Sheet 1 lzzsulazian lnsalazfion INVENTOR. flzza ew HIS A T TORZVE' Y July 28, .1959

A. HUFNAGEL ELECTROMAGNETIC SWITCHING DEVICES Filed 001:. 29, 1957 n IX -Insulation 3 Sheets-Sheet 2 Insulation I INVENTOR. Andflew Hufzzagel BY -W- H 1S ATTORNEY July 28, 1959 A. HUFNAGEL ELECTROMAGI IETIC SWITCHING DEVICES Filed Oct. 29, 1957 Insalazfion 4.9

-50 f! 60 I, @6 61 lo 15 i [j \l l 15 3 Sheets-Sheet 3 II.II I] "Insulation l"II II Fly 11.

Insulation .?7 50 Fig? 14.

' INVENTOR. flndflew Hui'nagel H15 ATTORNEY United States Patent ELECTROMAGNETIC SWITCHING DEVICES Andrew Hufuagel, Penn Township, Allegheny County, Pa., assignor to Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application October 29, 1957, Serial No. 693,070

'18 Claims. (Cl. 200-104) relay, it is necessary to completely withdraw the screws 7 from the contact stack. This procedure appreciably disturbs the alignment of the remaining contact springs and considerable adjustment of'the remaining contact springs is required to properly position their contact elements.

In prior art relays the boundaries for the operating stroke of the armature are. for. the most part established by an adjustable member which acts, as aback stop and by the pole face of the core which servesas a front stop for the armature. However, a non-metallic element of adjustable thickness is normally secured to the face of the armature to provide a residual air gap between armature and pole .face when the armature is in its attracted position. In some applications it becomes necessary to change the thickness of the non-magnetic element, which also changes the value of the armature stroke, so that it then becomes necessary to adjust the back stop member to obtain the correct stroke.

An object, therefore, of my invention is to provide an improved relay structure having a predetermined armature stroke, and means for controlling the air gap between the armature and the pole pieces without changing the limits of the armature stroke.

A further object of my invention is to obtain an improved relay structure in which a single bolt holds a contact stack assembly in fixed interrelationship to the associated parts of the relay such that the contact springs in the stack may be easily and readily changed without disassembling the relay.

Another object of my invention is to provide a multicontact relay of simple and compact construction which is efficient in operation and economical in manufacture and maintenance.

Another object of my invention is to provide a novel method for slidably mounting a relay at any point along a support structure.

In accordance with :my invention I attain the aforementioned objects by utilizing a rectangular .E-shaped core of magnetic material having an energizable coil winding secured on the middle leg thereof. .A flat U-shaped armature is spring mounted so as to be attracted toward the core upon energization of the coil. .At one end of the core, fixed and movable contact springs are supported in a spring pile-up assembly by insulating wafers to form a contact stack. A single bolt extends through the contact stack and engages the core, thereby holding the contact springs firmly clamped between the insulating wafers. The action of the contact springs is controlled by a fixed card of insulating material engaged by the tip ends of the 2,897,317 Patented July 28, 1959 fixed contact springs, and a movable card of insulating material responsive to armature movement which has projecting shoulders thereon engageable with the tip ends of the movable contact springs. An aperture through the fixed card receives a forward extension of the armature, the surfaces of the aperture providing front and back stops for the armature. In the particular embodiment disclosed herein the Contact stacks of individual relays may be of difierent dimensions and provision is made to freely slide each relay along a mounting structure to efliciently utilize the mounting space.

These and other features of my invention will become apparent from the following detailed description when read with reference to the accompanying drawings in which:

Fig. l is a plan view of the relay embodying my invention;

Fig. Z-isan "elevational view of the relay shown in Fig 1, portions thereof being shown in cross section;

Fig. 3 is a front end view-of the relay shown in Fig. 1;

Fig. 4 is a plan view of the magnetic core with coil mounted thereon and the nonmagnetic core plate;

Fig. 5 is a sectionalview taken along the line V--V of Fig. 2;

Fig. 6 is a sectional veiw. taken along the line VI--VI ofFig. 2; i i

Fig. 7 is a side view of Fig. 6;

Fig. 8 is a sectional view taken substantially along the line VIlIVIII of Fig. '2 showing the mounting clamp and screw; I

Fig. 9 is a sectional view taken along the line IX--IX of Fig. 3 showing the relative disposition of a fixed and a movable contact spring;

Fig. 10 is a sectional view taken substantially along the line X--X of Fig. 2;

Fig. 11 is a side view of Fig. 10;

Fig. 12 shows a typical form of a shim or spacer embodied in my invention;

Fig. 13 is a fragmentary view taken substantially along the line X--X of Fig. 2, but including the spacer shown in Fig. 12;

Fig. 14 is a side view of Fig. 13, and,

Fig. 15 is a front view of the operating ladder embodied in my invention.

I shall describe one form of relay embodying my invention, and shall then point out the novel features thereof in claims.

Similar reference characters refer to similar parts in each of the views.

Referring first to Figs. 1,, 2, 3 and 4, the relay comprises a rectangular E-shaped core having leg portions 1'3, 14 and 15 connected at one end by a back strap portion 17. An energizing coil winding 11 having external conductive strip leads 16 .is mounted on the center leg 14 of the core and is secured thereon by any suitable means, here shown as a wedge 18. The external strip leads 16 extend rearwardly from the coil winding 11 and are clamped between a molded block of insulating material 23 and coil terminals 22 which project rearwardly from the block 23 to provide a convenient means for making external electrical connections with the coil.

Pivotally mounted to cooperate with the upper or pole faces of the core legs 13, 14 and 1-5 is a U-shaped armature 27 having legs 27a which are substantially equal in length. The legs 27a-of the armature .27 extend rearwardly along the core legs 13 and 15 on either .side of the relay coil 11 in such positions that the bight of the U will cooperate with the forwardmost ends of the core legs .13, .14 and 15 in the energized condition of the coil winding 11.

The molded block 23 is provided with a plane surface 24 (Fig. 5,) against which the fiat-upper surface of the back strap portion 17 of the core is secured. Interposed between this flat upper surface of the back strap portion 17 and the plane surface 24 of the molded block 23 is an armature spring member 30. As best shown in Figs. 1 and 2, two parallel legs of the spring 30 extend forwardly of the block 23 along the core legs 13 and 15. The extreme forward ends of the legs of the spring member 30 are connected to the armature legs 27a by rivets 32, and oppositely disposed recesses 33 in the core legs 13 and 15 receive the rivets 32 to enable the armature to lie substantially flush against the pole faces of the core legs 13, 14 and 15 upon energization of the coil winding 11.

As best may be seen from Fig. 2, the block 23 supports a contact stack comprising springs such as front, heel and back springs 42, 43 and 44 and insulating wafers 85 interposed between the contact springs. A single bolt 77 extending through the contact stack clamps the springs 42, 43 and 44 between the insulating wafers 85 and holds the associated parts of the relay in fixed interrelationship. The movable contact springs 42 and 44 and the fixed contact springs 43 are arranged vertically adjacent each other in two columns and extend forwardly of the contact stack in approximate parallelism. The contact springs are of a flat rectangular configuration, and the movable springs 42' and 44 are bifurcated at their tip ends (Fig. 9) to reduce the possibility of contact chatter and of electrical failure due to lodgement of a nonconducting upwardly. Contact springs 42 and 44 are relatively long and flexible, and the pretensioning bend is made to be relatively large, with the result that any changes in vertical positioning at the tip ends of these springs will not appreciably affect their contacting pressures. The action of the movable springs 42 and 44 is controlled by a movable operating ladder 45 of insulating material (see Fig. 15) provided at its upper portion with projecting shoulders 47 which engage the contact springs 42 in the deenergized condition of the coil winding 11. The ladder 45 cooperates with the armature 27 and is forced downwardly upon energization of the relay winding 11 by engagement of a forwardly extending portion of the armature 27 with surfaces of an aperture provided in the ladder. Restoring springs 37 at the top of the contact stack continuously engage the uppermost shoulders 47 of the operating ladder 45 and are pretensioned upwardly to supply a vertical biasing force which restores the armature 27 and the operating ladder 45 to their unoperated positions upon deenergization of the relay winding 11.

As best shown in Fig. 2, a fixed ladder 49 of insulating material forward of the operating ladder 45 is connected to a fixed ladder plate 50 by rivets 51, and is provided with projecting shoulders 53 at its upper portion. The fixed contact springs 43 are pretensioned downwardly and their tip ends engage shoulders 53 of the fixed ladder 49, the heel springs 43 continuously exerting a downward force suficient to maintain the fixed ladder 49 in a fixed position perpendicular to the core axis.

In operation, the deenergization of the relay winding 11 causes the shoulders 47 of the operating ladder 45 to carry the front springs 42 clear of the fixed contact springs 43, the back contact springs 44 becoming engaged with the springs 43. Upon downward movement of the operating ladder 45 when the relay winding 11 is energized, the contact springs 44 are forcibly separated from the fixed contact springs 43 by shoulders 47' of the operating ladder 45, the front movable springs 42 engaging the fixed contact springs 43.

Referring now to Figs. 10 and 11, one of the novel features of my invention is a means to provide a predetermined value of armature stroke through control of the tolerances on the component parts of the relay, rather than by hand adjustment of the completed relay. As may be seen in Figs. 10 and 11, a forwardmost portion of the armature 27 extends through a rectangular aperture in the fixed ladder plate 50. The armature 27 is held in its unoperated or normal position by the action of the restoring springs 35 described hereinabove and is shown with its upper surface 58 in contact with upper aperture surfaces 60 of the plate 50. Upon energization of the relay winding 11, the armature 27 is attracted by the core legs 13, 14 and 15 and is limited in its downward motion by lower surfaces 61 of the aperture of the fixed ladder plate 50. The surfaces 61 of the plate 50 are normally coplanar with the pole faces of the core legs. Thus, it should be noted that the upper and lower surfaces 60 and 61 of the aperture of the fixed ladder plate 50 essentially provide front and back stops for the armature in the energized and deenergized condition of the relay winding.

A nonmagnetic core plat 63 (Fig. 4) extends adjacent the bottom surface of the forwardmost portion of core legs 13, 14 and 15 and is attached to the core legs by rivets 65. The core plate 63 serves to accurately position the core legs 13, 14 and 15 in relation to each other, and slots 66 in the coreplate 63 receive rectangular projections 67 of the fixed ladder plate 50 to ensure positive alignment of the fixed ladder 49 with the fixed contact springs 43.

It should therefore be noted that by controlling the tolerances on the thickness of the armature 27 and on the punched height of the aperture of the fixed ladder plate 50, the armature stroke for any application may be determined in the production stage of manufacture, and that in the assembled stage the need for hand adjustment of the armature stroke will be obviated.

Since it will become apparent in the following description of my present invention that the number of contact springs in the relay can be either increased or decreased, I provideas another novel feature a means for changing the air gap between the armature and the core to control the release characteristics of the relay to compensate for various contact spring loads, without changing the limits of the armature stroke. By this means the air gap can be conveniently adjusted without subsequent adjustment of the armature stroke. In order to accurately control the release characteristics of the relay, I provide a shim or spacer 68 as shown in Fig. 12. As best may be seen in Figs. 2, 13 and 14, legs 70 of the spacer 68 are inserted between the fixed ladder plate 50 and the nonmagnetic plate 63. The spacer legs 70 serve to raise the fixed ladder plate 50, the fixed ladder 49 and the surfaces 60 and 61 of the aperture of the fixed ladder, the armature 27, the movable operating ladder 45, and all fixed and movable contact springs. The downward force exerted on the fixed ladder 49 by the fixed contact springs 43 is sufficient to fix the spacer legs 70 between the 'core plate 63 and the fixed ladder plate 50. Thus, the lower limiting surfaces 61 of the fixed ladder plate 50 are raised a distance equal to the thickness of the spacer legs 70, and in the energized condition of the relay winding 11, the armature 27 is separated from the pole faces of the legs 13, 14 and 15 of the core by an air gap commensurate with the thickness of the spacer legs.

It should be pointed out, however, that the armature stroke remains defined by the upper and lower limiting surfaces 60 and 61 of the aperturein the fixed ladder plate 50, that because of the flexibility and relatively large pretension in thernovable contact springs only an insignificant change of pressure will occur between contact elements 38 and 39 for rather widely varying thicknesses of spacer 68.

The spacer $8 is further held in place by a removable label .holder 71, :as shown in Figs. 2 and 3. A hooked tab 73 extending from the label holder 71 rests over a groove of the fixed ladder 49, and a flexible tab 75 at the bottom of the label holder 71 overlaps and engage lower surface 76 of the nonmagnetic core plate 59. In this position the label holder 71 rests against the spacer 68, thereby further preventing the legs 70 of the spacer from being dislocated from between the fixed ladder plate 5 0 and the core plate 63.

As previously mentioned, certain :elements of the relay are held in fixed relationship to each other by the single bolt 77. Besides economyof manufacture, use of a single bolt in a relay :as embodied in my invention has the added advantage that the contact springs 42, 43 and 44 may be installed or removed without disassembling the relay. As shown .in Figs. l, 2 and 3., but more clearly illustrated in Fig. 5.,the bolt 77 passes through a conical spring washer 79 beneath the bolt head, through .a pressure plate 81, between the restoring :springs 37, and through an insulating plate .82. The bolt 77 further extends through the contactstack, between the coil terminal springs 22 and the externalfstrip) leads .16 of the coil 11, through the molded block 23 and the armature spring '30, and is received by a tapped hole through the back strap portion 17 of the core which holds the bolt 77 :in threaded engagement The bolt 77 can be tightened to .exert a compresrive force sufficient to firmly secure all of the parts through, or between which it passes. tightened conical washer spring.79 becomes somewhat compressed, and will thereafter serve to maintain adequate pressure in the stack, regardless of slight changes in the thicknesses of the stacked parts due to normal contraction and expansion.

As best shown in Fig. 2, .a rectangular tongue 83- on a lower surfaceof the block 23 is received by a machined groove 84 the back strap portion 17 to provide positive assurance again-st movement "of a twisting nature between the block and the core. Additional interlocking is provided in the contact stack by the insulating wafers .85 each of which includes twin bosses 87 (see Figs. 2 and 7) and matching grooves 89 on opposite sides of the wafers, the bosses 87 nesting in the grooves 89 of adjacent waters in the contact stack. The block '23 is formed at its top surface with similar grooves 90' which receive bosses 87 of the insulating wafer immediately adjacent the block. This interlocking feature positively fixes the contact stack relative to the block 23. The nested arrangement of the contact stack not only provides a very compact assembly but also prevents turning or misalignment of the contact springs despite the use of the single bolt to secure the stack.

As was mentioned previously, the contact springs 42, 43 and 44 in the contact stack may be individually installed or removed without disassembling the relay. As shown .in Figs. 6 and 7, each insulating wafer 85 is formed with a central rectangular cavity 86 which enables the pressure exerted by the bolt 77 to be distributed through the stack via the four well separated areas, -a, b, -c and .d; that is, two such areas a and b or c andvd for each spring. Because they are at equal radius from the axis of the bolt, the stack pressures will be substantially equal in each of the four areas, and these well separated pressures will provide additional assurance against turning movements of the various parts. Arcuate notches 91 in the contact springs are accurately located so that the springs are aligned against bosses 87 of the insulator 85. An arcuate notch 92 in each contact spring assures sufficient insulating distance between the spring and the bolt 77 and eliminates the need for an insulating sleeve around the bolt. To remove a spring from the contact stack, the external circuit wire is disconnected from soldering terminal 93, the pressure applied in the stack by the bolt 77 is somewhat reduced, and the spring slidably withdrawn in .a lateral direction from the stack;

As the bolt is 6 To install a contact spring .it is merely necessary to insert the spring between adjacent insulating wafers such that the arcuate notches 91 of the spring abut against the bosses 87, increase the pressure applied by the bolt 77, and connect the external circuit wire to the soldering terminal 93.

It will be observed that each insulating wafer 85 has tapered edges to provide for more convenient insertion of a contact spring between two wafers. With reference to Fig. 2 it will be observed that the tapered edges on these insulations provide also a greater electrical creepage distance between adjacent contact springs than could otherwise be obtained.

It should be pointed out that with the apparatus con.- structed in the manner just described, due to the equal forces exerted .on :each contact spring by the bolt 77, and because of the interlocking features of the contact stack, the alignment of thecontact springs remaining in the stack will be substantially unchanged whenever a contact spring is removed .for repair.

It should be further pointed out that with the apparatus constructed in the manner described, relays in manufacture can be conveniently assembled without contact springs, and then springs easily be installed as the required contact combinations to meet external circuit requirements become known.

'Since insome uses the height of the contact stack of j' .dual relays may not be the same, it should be readily understood that it is desirable to mount the relay so that the available space on a mounting structure is efficiently utilized. Referring now to Figs. 1, 2 and '8, the molded block 23 is formed with flat shoulders 95 which abut against inner surfaces of superposed parallel mounting rails 96 and with a rearwardly extending portion 23a disposed between the rails. The portion 23a of the block .23 is clamped rigidly between the rails 96 by means of a screw '97 and a clamp 98 which 'ab uts against the outer surface of the rails '96. The screw 97 passes centrally through the clamp 98, between the rails '96, and is received by a threaded metal insert 99 molded into a cavity of the block 23. By reducing the torque exerted by the screw '97 the relay may be freely slid to any point along the rails 96. The screw 97 can then be tightened to a high degree to maintain the relay rigid on the support structure. In practice it is expected that the rails 96 will be horizontally disposed.

It should therefore be pointed out that a relay as embodied in my invention may be rigid-1y mounted at any point along the rails, so that relays having a variety of heights of the contact stack can be substantially abutting, to "the end that a maximum number of relays will be accommodated between two rails of given length.

Although I have herein shown and described only one form of a relay embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my mvention.

Having thus described my invention, what I claim is:

l. A contact stack comprising a plurality of contact springs, insulating wafers interposed between adjacent ones of said springs, a supporting structure for said contact stack, each of said insulating 'wafers having at least one opening therethrough aligned with the opening of adjacent wafers for forming at least one passageway through said contact stack, bolt means extending through said opening securing said contact stack to said supporting structure, each of said contact springs being positioned adjacent to and free of confining engagement with said bolt means, and said bolt means being adjustably secured to said support structure to permit each of said springs to be removed from said contact stack without disassembling saidstack.

A contact stack comprising a plurality of contact springs, insulating wafers interposed between adjacent ones of said springs at one end of the springs, a sup port structure for said contact stack, each of said wafers having an opening therethrough aligned with the opening of adjacent wafers for forming a passageway through said contact stack, and a single mounting bolt extending through said opening in said contact stack, boss means on said wafers, and means on said springs engaging said boss means for positioning said springs between said wafers adjacent to and free of confining engagement with said bolt, said single bolt being adjustably secured to said support member for providing variable pressure for permitting each of said springs to be removed and replaced in said contact stack without disassembling said stack.

3. In a contact stack, in combination, a plurality of contact springs, insulating Wafers interposed between adjacent ones of said springs in spaced relationship, each of said wafers having an opening therethrough aligned with the opening of adjacent wafers for forming a passageway to said contact stack, a support structure, a single rod-like element extending through the passageway of said contact stack, boss means on said wafers interlocking adjacent wafers, means on said springs engaging said boss means for positioning said springs between said wafers adjacent to and free of confining engagement with said bolt, said single rod-like element being adjustably secured to said support structure and providing variable pressure for permitting edgewise slippage of each of said contact springs from said contact stack without disassembling said stack.

4. In a relay, a contact stack comprising a plurality of contact springs and insulating wafers interposed between adjacent ones of said springs in vertical stack relationship, a support structure, means for interlocking said contact stack with said support structure, said springs arranged in columns, the corresponding springs in each column being in the same plane, each of said wafers having an opening therethrough aligned with the openings of adjacent wafers, said openings of each of said insulating wafers disposed between said columns of said contact springs, and a single mounting bolt extending through the openings of said wafers and between said Nertical columns or springs, said springs being positioned free of confining engagement with said bolt, said mounting bolt being adjustably secured to said support structure to vary the pressure on said contact stack to permit individually removing said contact springs from said contact stack.

5. In a relay, in combination, a plurality of contact springs, insulating wafers interposed between adjacent ones of said contact springs to form a contact stack, a support structure, said springs and said contact stack being arranged in columns and extending from said contact stacks in approximate parallelism, each of said wafers having an opening therethrough aligned with the openings of adjacent wafers, said openings of said wafers being disposed between said columns of said contact springs, and a single mounting bolt extending through the openings of said wafers and between said columns of contact springs, said contact springs being free of confining engagement with said bolt, said mounting bolt making locking engagement with said support structure to clamp said contact springs between said insulating wafers and being adjustable to permit individual removal of said contact springs.

6. In a relay, a plurality of contact springs and insu lating wafers interposed between adjacent ones of said contact springs forming a contact stack, a support structure, said springs being arranged in columns with the corresponding springs in each column being in the same plane, each of said wafers having an opening therethrough in alignment with the openings of adjacent wafers, said springs in each of said columns being disposed on opposite sides of said openings, and a single mounting bolt extending through the openings of said wafers and between said vertical columns of said contact springs, each of said springs being free of confining engagement with said bolt, said single bolt passing through said openings and being adjustably secured to said support structure to permit varying the pressure on said contact stack to permit clamping said contact springs between said insulating wafers, and permitting individual removal of said contact springs.

7. In a relay, a core, a coil winding mounted on said core, fixed and movable contact springs, insulating wafers interposed between one end of adjacent ones of said springs forming a contact stack at the rear end of said core, a support structure, an armature attracted to said core upon energization of said coil winding, a core plate affixed to the forward end of said core, a first card of insulating material mounted transversely to said core plate and having projections thereon engaging the forward ends of said fixed springs to position said springs with respect to said movable springs, said first card having an aperture for receiving said armature and for controlling the stroke thereof, a second card of insulating material positioned adjacent said first card, said second card being responsive to armature movement and engageable with said movable springs, and a thin flat spacer provided with legs disposed between said first card and said core plate and arranged to control the air gap between said armature and said core in the energized condition of said coil winding.

8. In a relay, a core, an energizing coil winding mounted on said core, fixed and movable contact springs, a plurality of superposed insulating wafers interposed between one end of adjacent ones of said springs forming a contact stack at the rear end of said core, a support structure supporting said contact stack and interlocked with said contact stack and said core, an armature attracted to said core upon energization of said coil winding, a core plate affixed to said core and extending beyond the forward end of said core, a first card of insulating material having projections thereon engaging the forward ends of said fixed contact springs to position said springs with respect to said movable springs, said first card having an aperture for receiving said armature to provide front and back stops for said armature in the energized and deenergized condition of said coil winding, a second card of insulating material positioned adjacent said first card and responsive to armature movement and engageable with said movable springs, a thin L-shaped spacer having legs formed at right angles, the legs of said spacer being intermediate said first card and said core plate and arranged to control the air gap between said armature and said core in the energized condition of said coil winding, and means providing compressive force retaining said contact stack in fixed interrelationship to said support structure, the parts of said contact stack arranged to permit lateral movement of each of said contact springs from said contact stack without disassembling said stack upon releasing the pressure exerted by said means.

9. In a relay having a core and an energizable coil winding mounted on said core, fixed and movable contact springs having contact elements at one end thereof, insulating wafers interposed between adjacent ones of said springs at their other ends and positioned at the rear end of said core to form a contact stack, a support structure supporting said contact stack and interlocked with said stack and said core, an armature attracted to said core upon energization of said coil winding, a core plate attached to the lower surface of said core and extending beyond the forward end of said core, a fixed card of insulating material mounted transversely to said core plate and having projections thereon engaging the forward ends of said fixed contact springs adjacent said contact elements to position said contact elements of said fixed springs in relation to said contact elements of said movable springs, an aperture through said first card at its lower portion receiving said armature, said aperture having surfaces engaging said armature upon energization and deenergization of said coil winding, a second card of insulating material adjacent said first card being responsive to armature movement and engageable with said movable springs, a thin flat removable spacer having legs of predetermined thickness inserted intermediate said fixed card and said core plate for controlling the .air gap between said armature and said core, and bolt means retaining the elements of said contact stack in fixed intor-relationship, the spring and insulating wafers of said contact stack being arranged to permit each of said contact springs to be removed from said contact stack without disassembling said stack.

10. In combination in a relay having a core and an energizing coil winding mounted on said core, a plurality of fixed and movable contact springs each having contact elements at one end thereof, a plurality of insulating wafers interposed between adjacent ones of said contact springs at the ends opposite said contact elements, said springs and said wafers forming a contact stack at a rearward end of said core, a block .of insulating material having an opening therethrough and means for interlocking said block with said contact stack and said core, said springs in said contact stack being :arranged in vertical columns with the corresponding springs in each column being in the same plane, each of said wafers having an opening thereth-rough in alignment with the opening of adjacent wafers and aligned with the opening of said block to form a passageway through said contact stack, said corresponding springs in said vertical columns being disposed on opposite sides of said passageway, a fixed card of insulating material at the forward end of said core having projections thereon and being disposed in vertical relationship to said core, said projections of said fixed card engaging forward portions 'of said fixed springs adjacent said contact elements to position said springs in relation to said movable springs, an armature attracted toward said core upon energization of said coil winding, a movable card of insulating material positioned adjacent said fixed card and being responsive to armature movement upon energization of said coil winding, said movable card having projections thereon engageable with forward portions of said movable contact springs to carry said movable springs alternately in and out of engagement with said fixed contact springs, and bolt means extending through said continuous passageway of said contact stack between said vertical columns of said contact springs and passing through said opening of said block, said bolt means being adjustably secured to said core and normally pressing said wafers together to individually removably clamp said contact springs in predetermined position.

"11. In a relay having a core and an energizable coil winding secured to said core, a plurality of fixed and movable contact springs and a plurality of insulating wafers at the rear 'end of said core interposed between adjacent ones of said contact springs at one end thereof, an armature attracted toward said core upon energization of said coil winding, means for retaining said contact I springs in fixed relationship to said insulating wafers, a fixed card of insulating material at the forward end of said core having an aperture therethrough and having projections thereon at its upper portion engaging certain of said contact springs at their other ends to position "to said core, a plurality of fixed and movable contact springs, apl'urality of insulating wafers at the rear end of said core interposed between adjacent ones of said contact springs at one end thereof, said springs and said wafers comprising a contact stack, a block of insulating material supporting said contact stack, means for retaining said block fixed relative to said core, an armature attracted to said core upon energization of said coil, means retaining said contact springs clamped between said insulating wafers, a fixed card of insulating material having projections thereon at its upper portion for engaging said fixed contact springs at their other ends to position said springs in relation to said movable springs, .an aperture through said fixed card at its lower portion having first and second surfaces, and a movable card of insulating material responsive to armature movement positioned adjacent said fixed card and engageable with said movable contact springs to move said springs alternately in and out of engagement with said fixed springs, said armature extending transversely through said aperture on said fixed card and normally in engagement with a first surface of the aperture on said card in the 'deenergized condition of said coil winding, whereby upon energiza :tion of said coil winding said armature rests against a second surface of said aperture on said fixed card to provide a front stop for said armature.

13. In a relay having a core and a coil winding secured to said core, an armature attracted'toward said core upon energization of said coil winding, a plurality of fixed and movable contact springs, a plurality of insulating wafers at a rear end of said core interposed between one end of adjacent ones of said springs in stacked relationship forming a contact stack, a block of insulating material having an opening therethrough and means for interlocking said block with said contact stack and said core, each of said wafers having an opening therethrough in alignment with the openings of adjacent wafers and coaxial with the opening in said block, said springs in said contact stack being arranged in vertical columns with the corresponding springs in each column being in the same plane, said corresponding springs in said vertical columns being disposed on opposite sides of said opening through said contact stack, a bolt extending through the aligned openings of said contact stack and the opening of said block, said bolt being adjustably secured to said core to removably clamp said contact springs between said insulating wafers, a fixed card of insulating material at the forward end of said core having project-ions thereon in cooperative relationship with said fixed contact springs to position said springs in relation to said movable springs, an aperture through said fixed card at its lower portion having first and second surfaces, and a movable card of insulating material responsive to armature movement and engageable with said movable contact springs, said armature extending transversely through said aperture on said fixed card and normally in engagement with said first surface of said aperture of said card, said second surface of said aperture of said fixed card being engageable with said armature when said winding is energized, whereby in the energized and deencrgized conditions of said winding said first and second surfaces of said aperture of said fixed card cooperate with said armature to define the armature stroke.

14. In combination in a relay having a core, a coil winding mounted on said core, a block of insulating material having a central opening therethrough, a plurality of fixed and movable contact springs having contact elements thereon at one end for controlling external circuits, a plurality of superposed insulating wafers at the rear end of said core interposed between adjacent ones of said springs at the ends opposite said contact elements forming a contact stack, means for interlocking said block with said contact stack and said core, each of said wafers 'said contact stack in alignment with said Opening through said block, said springs in said contact stack being arranged in vertical columns with the corresponding springs in each column being in the same plane, said corresponding springs in each column being disposed on opposite sides of said passageway through said contact stack, a single rod-like member extending through the continuous passageway of said contact stack and the opening of said block and being adjustably secured to said core, said single member retaining said springs and said wafers of said contact stack in fixed interrelationship to each other, an armature attracted toward said core upon enerigization of said coil winding, a fixed card of insulating material at the forward end of said core having projections thereon in cooperative relationship with said fixed contact springs to position said contact springs in relation to said movable springs, an aperture through said card having first and second surfaces, and a movable card of insulating material adjacent said fixed card responsive to armature movement and being engageable with said movable contact springs to carry said springs alternately into and out of engagement with said fixed springs, said armature extending transversely through said aperture on said fixed card and normally in engagement with said first surface of said aperture of said fixed card, said second surface of said aperture of said fixed card being engageable with said armature when said winding becomes energized, whereby said first and second surfaces of said aperture of said fixed card provide predetermined front and back stops for said armature in the energized and deenergized conditions of said coil winding.

15. In a relay, in combination, a core having a pole face, a coil winding secured to said core, an armature operatively associated with said core, upon energization of said coil, a core plate aifixed to said core and extending beyond a forward end of said core, a plurality of fixed and movable contact springs, a plurality of insulating wafers at the rear end of said core, interposed between adjacent ones of said springs, said springs in combination with said wafers comprising a contact stack, means for clamping said contact springs between coil insulating wafers, means for engaging said movable springs to carry said movable springs alternately into and out of engagement with said fixed springs, a fixed card of insulating material at the forward end of said core having projections thereon at its upper portion engaging said fixed contact springs, said fixed card having an aperture therethrough at its lower portion to receive said armature, a first surface of said aperture being normally coplanar with the pole face of said core and providing a front stop for said armature in the energized condition of said coil winding, a second surface of said aperture normally providing a back stop for said armature in the deenergized condition of said coil winding, and means controlling the air gap between said armature and said core in the energized condition of said coil, said means comprising a thin L-shaped spacer of predetermined thickness with legs of said spacer being removably inserted between said core plate and said fixed card to raise said fixed card and said first and second surfaces of said aperture on said card, said armature being in engagement with said first surface of said aperture of said fixed card in the energized condition of said coil and being separated from the pole faces of said core by an air gap substantially equal to the thickness of said spacer.

16. In a relay, in combination, a core, and an energizable coil winding secured to said core, a nonmagnetic core plate affixed to saidcore and extending beyond the forward end. of said core, an armature operatively associated with said core, fixed and movable contact springs each having contact elements at one end thereof, insulating wafers at the rear end of said core interposed between adjacent ones of said contact springs at the ends opposite ,said contact elements to form a contact stack, a block of insulating rnaterial supporting said contact stack and means for interlocking'said block with said contact stack and said core, each of said wafers in said contact stack having an opening therethrough aligned with the openings of adjacent wafers to form a continuous passageway through said contact stack, said springs in said contact stack being arranged in vertical columns with the corresponding springs in each column being in the same plane, said corresponding springs in each column being disposed on opposite sides of said continuous passageway of said stack, an opening through said block axial to the openings of said wafers, a single rod-like member extending through said contact stack and through the opening of said block and being adjustably secured to said core to provide compressive force retaining said contact stack in fixed interrelationship to said relay, means for engaging said movable springs to carry said movable springs alternately in and out of engagement with said fixed springs, a fixed card of insulating material at the forward end of said core having projections thereon, said fixed contact springs engaging said projections on said card holding said card in fixed vertical juxtaposition against said core plate, said fixed card having an aperture therethrough for receiving said armature, a first surface of said aperture being normally coplanar with the pole faces of said core providing a front stop for said armature in the energized condition of said coil winding, a second surface of said aperture normally providing a back stop forsaid armature in the deenergized condition of said coil winding, said armature being movable between extreme positions of said aperture to define a predetermined armature stroke, and means controlling the air gap between said armature and said core in the energized condition of said coil, said means comprising a thin non-magnetic L's-haped spacer of predetermined thickness removably inserted between said fixed card and said core plate to raise said fixed card and said first and second surfaces of said aperture of said fixed card, whereby said armature engages said first surface of said aperture of said fixed card in the energized condition of said coil winding and is separated from the pole faces of said core by an air gap substantially equal to the thickness of said spacer, the predetermined armature stroke remaining unchanged.

17. In a relay, in combination, a core having a substantially pl'ane'pole surface, a coil winding mounted on said core, an armature operatively associated with said core, a nonmagnetic core plate connected to and extending beyond the forward end of said core, a plurality of fixed and movable contact springs, insulating wafers at the rear end of said core interposed between adjacent ones of said contact springs in vertical stacked relationship, said spr ings and said wafers comprising a contact stack, a support structure having an opening therethrough, means interlocking said support structure with said contact stack and said core, each of said wafers having an opening therethrough vertically aligned with the openings of adjacent wafers, said aligned openings forming a continuous passageway through said contact stack in alignment with the opening of said support structure, said springs in said contact stack being arranged in vertical columns with the corresponding springs in each column being in the same plane, said corresponding springs in each column being disposed on opposite sides of said continuous passageway of said stack, a single bolt extending axially through the openings of said wafers and passing through the opening of said support structure, said single bolt being adjustably secured to said core to retain said contact springs individually removably clamped between said insulating wafers, a fixed card of insulating material at the forward end of said core having projections thereon at its upper portion, said fixed contact springs engaging said projections on said card holding said card in fixed vertical juxtaposition against said core plate, said fixed card having an aperture through its lower portion to receive said armature, a

first surface of said aperture being normally coplanar with the pole face of said core providing a front stop for said armature in the energized condition of said coil Winding, a second surface of said aperture normally providing a back stop for said armature in the deenergized condition of said coil winding, said armature being movable between extreme positions of said aperture to define a predetermined armature stroke, and means controlling the air gap between said armature and said core in the energized condition of said coil, said means comprising a thin flat L-shaped spacer having legs of predetermined thickness removably inserted between said fixed card and said core plate raising said fixed card and said first and second surfaces of said aperture of said fixed card, whereby said armature is in engagement with said first surface of said aperture of said fixed card in the energized condition of said coil winding and is separated from the pole faces of said core by an air gap substantially equal to the thickness of said legs of said spacer, the predetermined armature stroke remaining unchanged,

18. A mounting structure for mounting a relay between spaced rails, comprising a relay support including a main frame and a reduced extending portion, said extending portion arranged to be insertable between said rails and said frame arranged to bear against the surface of said rails, a mounting clamp comprising a mid portion and flange portions at opposite ends of said mid portion, said mid portion of said clamp arranged to receive said ex tending portion in intimate relation and having an opening therethrough and said flange portions being engageable with adjacent rails and a mounting screw extending through said opening of said clamp and engaging said clamp, said screw engaging said extending portion of said relay support to draw said main frame of said relay support firmly against said rails, said screw being adjustable to control the force exerted by said mounting screw to permit said mounting structure to be slidable between said mounting rails and to permit securing of said relay at a desired point on said rails.

References Cited in the file of this patent UNITED STATES PATENTS 2,277,443 Livingston Mar. 24, 1942 2,321,834 Marco et a1. June 15, 1943 2,610,998 Lockhart Sept. 16, 1952 2,740,871 Vigren et a1. Apr. 3, 1956 FOREIGN PATENTS 608,960 Great Britain Sept. 23, 1948 

